1. Field of the Invention
The present invention relates to a method and apparatus for making pellets of wood meal compound, and more particularly to a novel improvement in which synthetic resin material and wood meal material are supplied into a hopper without employing a side feeder, and as the results, the material can be sufficiently kneaded in a kneading section which is longer than in the prior art, without increasing a total length of the apparatus, thus enhancing properties of the product.
2. Related Art
As a conventional cutting device for the wood meal compound in which wood meal is used as material for mixture, the following art has been already disclosed in Japanese Patent Publication No. 2001-129870A. Specifically, designated by reference numeral 30 in FIG. 3, is an apparatus for making pellets of wood meal compound employing a twin screw type kneading and extruding machine 1. In a side area of this twin screw type kneading and extruding machine 1, there is provided a screw type side feeder 2. The above mentioned twin screw type kneading and extruding machine 1 includes a drive mechanism 31 connected thereto in a most upstream position, and further includes in series in a distal end direction, in other words, in a downstream direction, a resin supply hopper 3, a first kneading section 4, a screw type side feeder 2, a degassing cylinder 5, a second kneading section 6, and an open vent section 7 each of which is composed of a single cylinder block, a vacuum drawing vent section 8 composed of three cylinder blocks, an extruding section 9 composed of two cylinder blocks, and a die 10.
In the apparatus 30 for making pellets of wood meal compound constructed as described above, after those cylinders in the respective sections of the twin screw type kneading and extruding machine 1 have been heated up to a predetermined temperature, the drive mechanism 31 is actuated to rotate a twin screw 1a in order to supply the synthetic resin material from the resin supply hopper 3.
On the other hand, in the side feeder 2 too, a drive mechanism 2a is actuated to rotate a screw 2b in order to supply the wood meal material in a form of flour. This wood meal material is transported through the second kneading section 6 to in a distal end direction by means of the rotating screw 2b, heated up together with the synthetic resin material, and kneaded and melted by the heat and by shearing action of the rotating twin screw 1a. 
The wood meal material and the synthetic resin material which have been kneaded and melted pass through the degassing cylinder 5, then kneaded and melted in the second kneading section 6, and thereafter, extruded from the die 10 through the open vent section 7, the vacuum drawing vent section 8, and the extruding section 9. This die 10 constitutes a part of a cutting device 100, and the composite resin material formed in a rod-like or a sheet-like shape will be cut and pelletized through this die 10.
Since the conventional method and apparatus for making pellets of wood meal compound have had the above described structure, there have been such problems as described below.
In particular, because there has been provided the side feeder for supplying the wood meal material in a side area of the twin screw type kneading and extruding machine, the respective kneading sections have had a small number of blocks, and consequently, kneading degree has been insufficient, resulting in low strength of the produced composite resin material. Moreover, the wood meal material has been added to the synthetic resin material which had passed the first kneading section, to be mixed and kneaded in the second kneading section. However, the synthetic resin material in a semi-melted condition is low in viscosity and weak in shearing action to be applied by the screw, which leads to insufficient kneading and dispersion of the added wood meal material. As the results, a non-uniform composite resin material which has low strength has been produced.